/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2007 Sun Microsystems, Inc.  Portions Copyrighted 2008 Richard Schilling.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 *
 * Contributor(s): Richard Schilling (coderroadie@gmail.com)
 *
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package com.sun.mail.iap;

import java.io.*;
import java.util.*;
import com.sun.mail.util.*;

/**
 * This class represents a response obtained from the input stream
 * of an IMAP server.
 * 
 * @author John Mani
 */

public class Response {

    protected int index;  // internal index (updated during the parse)
    protected int pindex; // index after parse, for reset
    protected int size;   // number of valid bytes in our buffer
    protected byte[] buffer = null;
    protected int type = 0;
    protected String tag = null;

    private static final int increment = 100;

    // The first and second bits indicate whether this response
    // is a Continuation, Tagged or Untagged
    public final static int TAG_MASK = 0x03;
    public final static int CONTINUATION = 0x01;
    public final static int TAGGED = 0x02;
    public final static int UNTAGGED = 0x03;

    // The third, fourth and fifth bits indicate whether this response
    // is an OK, NO, BAD or BYE response
    public final static int TYPE_MASK = 0x1C;
    public final static int OK = 0x04;
    public final static int NO = 0x08;
    public final static int BAD = 0x0C;
    public final static int BYE = 0x10;

    // The sixth bit indicates whether a BYE response is synthetic or real
    public final static int SYNTHETIC = 0x20;

    public Response(String s) {
        buffer = ASCIIUtility.getBytes(s);
        size = buffer.length;
        parse();
    }

    /**
     * Read a new Response from the given Protocol
     * 
     * @param p the Protocol object
     */
    public Response(Protocol p) throws IOException, ProtocolException {
        // read one response into 'buffer'
        ByteArray ba = p.getResponseBuffer();
        ByteArray response = p.getInputStream().readResponse(ba);
        buffer = response.getBytes();
        size = response.getCount() - 2; // Skip the terminating CRLF

        parse();
    }

    /**
     * Copy constructor.
     */
    public Response(Response r) {
        index = r.index;
        size = r.size;
        buffer = r.buffer;
        type = r.type;
        tag = r.tag;
    }

    /**
     * Return a Response object that looks like a BYE protocol response.
     * Include the details of the exception in the response string.
     */
    public static Response byeResponse(Exception ex) {
        String err = "* BYE JavaMail Exception: " + ex.toString();
        err = err.replace('\r', ' ').replace('\n', ' ');
        Response r = new Response(err);
        r.type |= SYNTHETIC;
        return r;
    }

    private void parse() {
        index = 0; // position internal index at start

        if (buffer[index] == '+') { // Continuation statement
            type |= CONTINUATION;
            index += 1; // Position beyond the '+'
            return;	// return
        } else if (buffer[index] == '*') { // Untagged statement
            type |= UNTAGGED;
            index += 1; // Position beyond the '*'
        } else {  // Tagged statement
            type |= TAGGED;
            tag = readAtom();	// read the TAG, index positioned beyond tag
        }

        int mark = index; // mark
        String s = readAtom();	// updates index
        if (s == null)
            s = "";		// avoid possible NPE
        if (s.equalsIgnoreCase("OK"))
            type |= OK;
        else if (s.equalsIgnoreCase("NO"))
            type |= NO;
        else if (s.equalsIgnoreCase("BAD"))
            type |= BAD;
        else if (s.equalsIgnoreCase("BYE"))
            type |= BYE;
        else
            index = mark; // reset

        pindex = index;
        return;
    }

    public void skipSpaces() {
        while (index < size && buffer[index] == ' ')
            index++;
    }

    /**
     * Skip to the next space, for use in error recovery while parsing.
     */
    public void skipToken() {
        while (index < size && buffer[index] != ' ')
            index++;
    }

    public void skip(int count) {
        index += count;
    }

    public byte peekByte() {
        if (index < size)
            return buffer[index];
        else
            return 0;		// XXX - how else to signal error?
    }

    /**
     * Return the next byte from this Statement.
     * 
     * @return the next byte.
     */
    public byte readByte() {
        if (index < size)
            return buffer[index++];
        else
            return 0;		// XXX - how else to signal error?
    }

    /**
     * Extract an ATOM, starting at the current position. Updates
     * the internal index to beyond the Atom.
     * 
     * @return an Atom
     */
    public String readAtom() {
        return readAtom('\0');
    }

    /**
     * Extract an ATOM, but stop at the additional delimiter
     * (if not NUL). Used to parse a response code inside [].
     */
    public String readAtom(char delim) {
        skipSpaces();

        if (index >= size) // already at end of response
            return null;

        /*
         * An ATOM is any CHAR delimited by :
         * SPACE | CTL | '(' | ')' | '{' | '%' | '*' | '"' | '\'
         */
        byte b;
        int start = index;
        while (index < size && ((b = buffer[index]) > ' ') && b != '(' && b != ')' && b != '%'
                && b != '*' && b != '"' && b != '\\' && b != 0x7f && (delim == '\0' || b != delim))
            index++;

        return ASCIIUtility.toString(buffer, start, index);
    }

    /**
     * Read a string as an arbitrary sequence of characters,
     * stopping at the delimiter Used to read part of a
     * response code inside [].
     */
    public String readString(char delim) {
        skipSpaces();

        if (index >= size) // already at end of response
            return null;

        int start = index;
        while (index < size && buffer[index] != delim)
            index++;

        return ASCIIUtility.toString(buffer, start, index);
    }

    public String[] readStringList() {
        skipSpaces();

        if (buffer[index] != '(') // not what we expected
            return null;
        index++; // skip '('

        Vector v = new Vector();
        do {
            v.addElement(readString());
        } while (buffer[index++] != ')');

        int size = v.size();
        if (size > 0) {
            String[] s = new String[size];
            v.copyInto(s);
            return s;
        } else
            // empty list
            return null;
    }

    /**
     * Extract an integer, starting at the current position. Updates the
     * internal index to beyond the number. Returns -1 if a number was
     * not found.
     * 
     * @return a number
     */
    public int readNumber() {
        // Skip leading spaces
        skipSpaces();

        int start = index;
        while (index < size && Character.isDigit((char) buffer[index]))
            index++;

        if (index > start) {
            try {
                return ASCIIUtility.parseInt(buffer, start, index);
            } catch (NumberFormatException nex) {}
        }

        return -1;
    }

    /**
     * Extract a long number, starting at the current position. Updates the
     * internal index to beyond the number. Returns -1 if a long number
     * was not found.
     * 
     * @return a long
     */
    public long readLong() {
        // Skip leading spaces
        skipSpaces();

        int start = index;
        while (index < size && Character.isDigit((char) buffer[index]))
            index++;

        if (index > start) {
            try {
                return ASCIIUtility.parseLong(buffer, start, index);
            } catch (NumberFormatException nex) {}
        }

        return -1;
    }

    /**
     * Extract a NSTRING, starting at the current position. Return it as
     * a String. The sequence 'NIL' is returned as null
     * NSTRING := QuotedString | Literal | "NIL"
     * 
     * @return a String
     */
    public String readString() {
        return (String) parseString(false, true);
    }

    /**
     * Extract a NSTRING, starting at the current position. Return it as
     * a ByteArrayInputStream. The sequence 'NIL' is returned as null
     * NSTRING := QuotedString | Literal | "NIL"
     * 
     * @return a ByteArrayInputStream
     */
    public ByteArrayInputStream readBytes() {
        ByteArray ba = readByteArray();
        if (ba != null)
            return ba.toByteArrayInputStream();
        else
            return null;
    }

    /**
     * Extract a NSTRING, starting at the current position. Return it as
     * a ByteArray. The sequence 'NIL' is returned as null
     * NSTRING := QuotedString | Literal | "NIL"
     * 
     * @return a ByteArray
     */
    public ByteArray readByteArray() {
        /*
         * Special case, return the data after the continuation uninterpreted.
         * It's usually a challenge for an AUTHENTICATE command.
         */
        if (isContinuation()) {
            skipSpaces();
            return new ByteArray(buffer, index, size - index);
        }
        return (ByteArray) parseString(false, false);
    }

    /**
     * Extract an ASTRING, starting at the current position
     * and return as a String. An ASTRING can be a QuotedString, a
     * Literal or an Atom
     * Any errors in parsing returns null
     * ASTRING := QuotedString | Literal | Atom
     * 
     * @return a String
     */
    public String readAtomString() {
        return (String) parseString(true, true);
    }

    /**
     * Generic parsing routine that can parse out a Quoted-String,
     * Literal or Atom and return the parsed token as a String
     * or a ByteArray. Errors or NIL data will return null.
     */
    private Object parseString(boolean parseAtoms, boolean returnString) {
        byte b;

        // Skip leading spaces
        skipSpaces();

        b = buffer[index];
        if (b == '"') { // QuotedString
            index++; // skip the quote
            int start = index;
            int copyto = index;

            while ((b = buffer[index]) != '"') {
                if (b == '\\') // skip escaped byte
                    index++;
                if (index != copyto) { // only copy if we need to
                    // Beware: this is a destructive copy. I'm
                    // pretty sure this is OK, but ... ;>
                    buffer[copyto] = buffer[index];
                }
                copyto++;
                index++;
            }
            index++; // skip past the terminating quote

            if (returnString)
                return ASCIIUtility.toString(buffer, start, copyto);
            else
                return new ByteArray(buffer, start, copyto - start);
        } else if (b == '{') { // Literal
            int start = ++index; // note the start position

            while (buffer[index] != '}')
                index++;

            int count = 0;
            try {
                count = ASCIIUtility.parseInt(buffer, start, index);
            } catch (NumberFormatException nex) {
                // throw new ParsingException();
                return null;
            }

            start = index + 3; // skip "}\r\n"
            index = start + count; // position index to beyond the literal

            if (returnString) // return as String
                return ASCIIUtility.toString(buffer, start, start + count);
            else
                return new ByteArray(buffer, start, count);
        } else if (parseAtoms) { // parse as an ATOM
            int start = index;	// track this, so that we can use to
            // creating ByteArrayInputStream below.
            String s = readAtom();
            if (returnString)
                return s;
            else
                // *very* unlikely
                return new ByteArray(buffer, start, index);
        } else if (b == 'N' || b == 'n') { // the only valid value is 'NIL'
            index += 3; // skip past NIL
            return null;
        }
        return null; // Error
    }

    public int getType() {
        return type;
    }

    public boolean isContinuation() {
        return ((type & TAG_MASK) == CONTINUATION);
    }

    public boolean isTagged() {
        return ((type & TAG_MASK) == TAGGED);
    }

    public boolean isUnTagged() {
        return ((type & TAG_MASK) == UNTAGGED);
    }

    public boolean isOK() {
        return ((type & TYPE_MASK) == OK);
    }

    public boolean isNO() {
        return ((type & TYPE_MASK) == NO);
    }

    public boolean isBAD() {
        return ((type & TYPE_MASK) == BAD);
    }

    public boolean isBYE() {
        return ((type & TYPE_MASK) == BYE);
    }

    public boolean isSynthetic() {
        return ((type & SYNTHETIC) == SYNTHETIC);
    }

    /**
     * Return the tag, if this is a tagged statement.
     * 
     * @return tag of this tagged statement
     */
    public String getTag() {
        return tag;
    }

    /**
     * Return the rest of the response as a string, usually used to
     * return the arbitrary message text after a NO response.
     */
    public String getRest() {
        skipSpaces();
        return ASCIIUtility.toString(buffer, index, size);
    }

    /**
     * Reset pointer to beginning of response.
     */
    public void reset() {
        index = pindex;
    }

    public String toString() {
        return ASCIIUtility.toString(buffer, 0, size);
    }

}
